diff options
Diffstat (limited to 'arch/arc/mm/fault.c')
| -rw-r--r-- | arch/arc/mm/fault.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c new file mode 100644 index 000000000000..689ffd86d5e9 --- /dev/null +++ b/arch/arc/mm/fault.c @@ -0,0 +1,227 @@ +/* Page Fault Handling for ARC (TLB Miss / ProtV) + * + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/signal.h> +#include <linux/interrupt.h> +#include <linux/sched.h> +#include <linux/errno.h> +#include <linux/ptrace.h> +#include <linux/uaccess.h> +#include <linux/kdebug.h> +#include <asm/pgalloc.h> + +static int handle_vmalloc_fault(struct mm_struct *mm, unsigned long address) +{ + /* + * Synchronize this task's top level page-table + * with the 'reference' page table. + */ + pgd_t *pgd, *pgd_k; + pud_t *pud, *pud_k; + pmd_t *pmd, *pmd_k; + + pgd = pgd_offset_fast(mm, address); + pgd_k = pgd_offset_k(address); + + if (!pgd_present(*pgd_k)) + goto bad_area; + + pud = pud_offset(pgd, address); + pud_k = pud_offset(pgd_k, address); + if (!pud_present(*pud_k)) + goto bad_area; + + pmd = pmd_offset(pud, address); + pmd_k = pmd_offset(pud_k, address); + if (!pmd_present(*pmd_k)) + goto bad_area; + + set_pmd(pmd, *pmd_k); + + /* XXX: create the TLB entry here */ + return 0; + +bad_area: + return 1; +} + +void do_page_fault(struct pt_regs *regs, int write, unsigned long address, + unsigned long cause_code) +{ + struct vm_area_struct *vma = NULL; + struct task_struct *tsk = current; + struct mm_struct *mm = tsk->mm; + siginfo_t info; + int fault, ret; + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE | + (write ? FAULT_FLAG_WRITE : 0); + + /* + * We fault-in kernel-space virtual memory on-demand. The + * 'reference' page table is init_mm.pgd. + * + * NOTE! We MUST NOT take any locks for this case. We may + * be in an interrupt or a critical region, and should + * only copy the information from the master page table, + * nothing more. + */ + if (address >= VMALLOC_START && address <= VMALLOC_END) { + ret = handle_vmalloc_fault(mm, address); + if (unlikely(ret)) + goto bad_area_nosemaphore; + else + return; + } + + info.si_code = SEGV_MAPERR; + + /* + * If we're in an interrupt or have no user + * context, we must not take the fault.. + */ + if (in_atomic() || !mm) + goto no_context; + +retry: + down_read(&mm->mmap_sem); + vma = find_vma(mm, address); + if (!vma) + goto bad_area; + if (vma->vm_start <= address) + goto good_area; + if (!(vma->vm_flags & VM_GROWSDOWN)) + goto bad_area; + if (expand_stack(vma, address)) + goto bad_area; + + /* + * Ok, we have a good vm_area for this memory access, so + * we can handle it.. + */ +good_area: + info.si_code = SEGV_ACCERR; + + /* Handle protection violation, execute on heap or stack */ + + if (cause_code == ((ECR_V_PROTV << 16) | ECR_C_PROTV_INST_FETCH)) + goto bad_area; + + if (write) { + if (!(vma->vm_flags & VM_WRITE)) + goto bad_area; + } else { + if (!(vma->vm_flags & (VM_READ | VM_EXEC))) + goto bad_area; + } + +survive: + /* + * If for any reason at all we couldn't handle the fault, + * make sure we exit gracefully rather than endlessly redo + * the fault. + */ + fault = handle_mm_fault(mm, vma, address, flags); + + /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */ + if (unlikely(fatal_signal_pending(current))) { + if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY)) + up_read(&mm->mmap_sem); + if (user_mode(regs)) + return; + } + + if (likely(!(fault & VM_FAULT_ERROR))) { + if (flags & FAULT_FLAG_ALLOW_RETRY) { + /* To avoid updating stats twice for retry case */ + if (fault & VM_FAULT_MAJOR) + tsk->maj_flt++; + else + tsk->min_flt++; + + if (fault & VM_FAULT_RETRY) { + flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; + goto retry; + } + } + + /* Fault Handled Gracefully */ + up_read(&mm->mmap_sem); + return; + } + + /* TBD: switch to pagefault_out_of_memory() */ + if (fault & VM_FAULT_OOM) + goto out_of_memory; + else if (fault & VM_FAULT_SIGBUS) + goto do_sigbus; + + /* no man's land */ + BUG(); + + /* + * Something tried to access memory that isn't in our memory map.. + * Fix it, but check if it's kernel or user first.. + */ +bad_area: + up_read(&mm->mmap_sem); + +bad_area_nosemaphore: + /* User mode accesses just cause a SIGSEGV */ + if (user_mode(regs)) { + tsk->thread.fault_address = address; + tsk->thread.cause_code = cause_code; + info.si_signo = SIGSEGV; + info.si_errno = 0; + /* info.si_code has been set above */ + info.si_addr = (void __user *)address; + force_sig_info(SIGSEGV, &info, tsk); + return; + } + +no_context: + /* Are we prepared to handle this kernel fault? + * + * (The kernel has valid exception-points in the source + * when it acesses user-memory. When it fails in one + * of those points, we find it in a table and do a jump + * to some fixup code that loads an appropriate error + * code) + */ + if (fixup_exception(regs)) + return; + + die("Oops", regs, address, cause_code); + +out_of_memory: + if (is_global_init(tsk)) { + yield(); + goto survive; + } + up_read(&mm->mmap_sem); + + if (user_mode(regs)) + do_group_exit(SIGKILL); /* This will never return */ + + goto no_context; + +do_sigbus: + up_read(&mm->mmap_sem); + + if (!user_mode(regs)) + goto no_context; + + tsk->thread.fault_address = address; + tsk->thread.cause_code = cause_code; + info.si_signo = SIGBUS; + info.si_errno = 0; + info.si_code = BUS_ADRERR; + info.si_addr = (void __user *)address; + force_sig_info(SIGBUS, &info, tsk); +} |